In a current communication network, with the increasing importance of the Internet, all the communication services are being packetized. And to stably provide a voice service of a voice over Internet protocol (VoIP) and an image service of an Internet protocol television (IPTV) in a wired/wireless packet network, a technology of a highly reliable packet transport layer (hereinafter, PTL) scheme is being applied.
In order to increase the diversity and the reliability of transport, the PTL scheme enables all the communication services to be performed based on a packet, and accurately transports the packet at a circuit level. So, the above scheme guarantees the transport quality of the packet. But because the above scheme is not applied to an access network, there was a problem in that the above scheme does not guarantee transport quality between customer terminations and is limited to communication between local stations.
An existing passive optical network (hereinafter, PON) scheme includes an Ethernet PON (hereinafter, E-PON) scheme and a gigabit PON (hereinafter, G-PON) scheme. The E-PON scheme is suitable for communication using Ethernet protocol and thus, is applied to an Ethernet network including an Ethernet switch. The G-PON scheme is a scheme enabling an Ethernet and asynchronous transfer mode (ATM) and circuit communication. In general, the above PON schemes are easy to be applied to the Ethernet network and are not suitable for being applied to a PTL network, where connection establishment is needed for guaranteeing the quality.
The detailed description with respect to the above problem will be described through a PTL scheme applied to E-PON.
A packet transmitted from an optical network unit (hereinafter, ONU) or an optical network terminal (hereinafter, ONT) of a customer termination is aggregated at a packet switch of one party via an optical line termination (hereinafter, OLT). The aggregated packets are transported to a packet switch of another party via a packet switch or a router of a metro network and a core network and thereby are transmitted to another customer termination.
In general, in the metro network and the core network, a channel is established by a connection management server and a state of the connection is managed. However, in the access network between an OLT and an ONU/ONT, only a physical link is managed by an E-PON server and a connection of a logical level does not exist.
Accordingly, when an error occurs in transferred information, there was a problem in that even though it is possible to verify whether the error occurred in the metro network and the core network, it is difficult to verify whether the error occurred in the access network.